MONDAY, July 16, 2018 (HealthDay News) — A considerable number of randomized controlled trials (RCTs) of probiotics, prebiotics, or synbiotics do not report harms-related data and/or safety results, according to a review published online July 17 in the Annals of Internal Medicine.

Aïda Bafeta, Ph.D., from the Université Paris Descartes-Sorbonne Paris Cité, and colleagues examined how harms-related information is reported in publications of RCTs of probiotics, prebiotics, and synbiotics. RCTs included in the review assessed the safety or efficacy of at least one intervention versus any control for any clinical condition.

The researchers found that 88 percent of the 384 trials conducted in healthy volunteers (136 trials) or patients with any of several medical conditions (248 trials) were published in specialty journals. Probiotics were most often evaluated (69 percent). Outpatients and high-risk patients were enrolled in studies of persons with medical conditions (195 and 53, respectively). In 28, 37, and 80 percent of trials, no harm-related data, safety results, and number of serious adverse events (SAEs) per study group were reported, respectively. Thirty-seven and 16 percent of the 242 studies mentioning harm-related results used only generic statements to describe AEs and used inadequate metrics, respectively. Ninety-eight percent of trials did not give a definition for AEs or SAEs, the number of withdrawals due to harms, or the number of AEs or SAEs per study group with denominators.

“In summary, most studies of probiotics, prebiotics, and synbiotics lack key safety parameters, raising doubts about the confidence we can have in conclusions about the safety of these interventions,” the authors write.